How are you loading the NewDataSet? Do you manually create the tables and the columns in them? If so, can you get the schema from the CurrentDataSet before you load data into the NewDataSet? That way you'd know that all of your relationships will match. See MSDN: http://msdn.microsoft.com/en-us/library/system.data.common.dbdataadapter.fillschema(v=vs.71).aspx